A1. Enrollment

National

Enrollment projections were based on projected enrollment rates,
by age and sex, which were applied to population projections by
age and sex developed by the Bureau of the Census. These enrollment
rates were projected by taking into account the most recent trends,
as well as the effects of economic conditions and demographic
changes on a person's decision to enter college. The enrollment
rates were then used in the Education Forecasting Model (EDMOD),
which consists of age-specific rates by sex and by enrollment
levels.

Education Forecasting Model

The first stage of EDMOD is an age-specific enrollment model in which enrollment rates are projected and applied to age-specific population projections. This stage, which is used separately for each sex, includes the following categories: (1) full-time college enrollment, and (2) part-time college enrollment. Within an enrollment category, where applicable, enrollment rates were projected by individual ages 16 through 24 and for the age groups 25 to 29, 30 to 34, and 35 years and over.

Enrollments by age and age groups from the Bureau of the Census were adjusted
to NCES totals to compute enrollment rates for 1972 through 1999.
Different assumptions were made to produce low, middle, and high
alternative projections of enrollment rates to the year 2011.

Projections of full-time and part-time college enrollments were
considered only for ages 16 and over. College enrollment is negligible
for earlier ages. Three alternative projections were made using
various economic assumptions. Table
A1.1 shows enrollment rates for 1999 and middle alternative
projected enrollment rates for 2006 and 2011. Table
A1.2 shows the equations used to project enrollment rates
for men by attendance status. Table
A1.3 shows the equations used to project enrollment rates
for women by attendance status.

Enrollment in Public Elementary and Secondary
Schools, by Grade Group and Organizational Level

The second stage of EDMOD projects public enrollment in elementary
and secondary schools by grade group and by organizational level.
Public enrollments by age were based on enrollment rate projections
for nursery and kindergarten, grade 1, elementary ungraded and
special, secondary ungraded and special, and postgraduate enrollment.
Grade progression rate projections were used for grades 2 through
12. Table A1.4 shows the public
school enrollment rates and table
A1.5 shows the public school grade progression rates for 1999
and projections for 2006 and 2011. The projected rates in tables
A1.4 and A1.5 were used
to compute the projections of enrollments in elementary and secondary
schools, by grade, shown in table
1.

College Enrollment, by Sex, Attendance Status,
and Level Enrolled; and by Type and Control of Institution

The third stage of EDMOD projects enrollments in institutions
of higher education, by sex, attendance status, and level enrolled
by student and by type and control of institution. For each age
group, the percent of total enrollment by age, attendance status,
level enrolled, and type of institution was projected. These projections
for 2006 and 2011 are shown in tables
A1.6 and A1.7, along with
actual values for 1999. For all projections, it was assumed that
there was no enrollment in 2-year institutions at the postbac-calaureate
level (graduate and first-professional).

The projected rates in tables
A1.6 and A1.7 were then
adjusted to agree with the projected age-specific enrollment rates
in the first stage of EDMOD. The adjusted rates were then applied
to the projected enrollments by age group, sex, and attendance
status from the first stage of EDMOD to obtain projections by
age group, sex, attendance status, level enrolled, and type of
institution.

For each enrollment category-sex, attendance status, level enrolled,
and type of institution-public enrollment was projected as a percent
of total enrollment. Projections for 2006 and 2011 are shown in
table A1.8, along with actual
percents for 1999. The projected rates were then applied to the
projected enrollments in each enrollment category to obtain projections
by control of institution.

For each category by sex, enrollment level, and type and control
of institution, graduate enrollment was projected as a percent
of postbaccalaureate enrollment. Actual rates for 1999 and projections
for 2006 and 2011 are shown in table
A1.9. The projected rates in table
A1.9 were then applied to projections of postbaccalaureate
enrollment to obtain graduate and first-professional enrollment
projections by sex, attendance status, and type and control of
institution.

Full-Time-Equivalent Enrollment, by Type and
Control of Institution and by Level Enrolled

The fourth stage of EDMOD projects full-time-equivalent enrollment,
by type and control of institution and by level enrolled. For
each enrollment category by level enrolled and by type and control
of institution, the full-time-equivalent of part-time enrollment
was projected as a percent of part-time enrollment. Actual percents
for 1999 and projections for 2006 and 2011 are shown in table
A1.10.

These projected percents were applied to projections of enrollment
by level enrolled and by type and control of institution from
the third stage of EDMOD. The projections were added to projections
of full-time enrollment (from the previous stage) to obtain projections
of full-time-equivalent enrollment.

An analysis of projection errors from the past 18 editions of Projections of Education Statistics indicates that the mean absolute percentage errors (MAPEs) for lead times of 1, 2, 5, and 10 years out for projections of public school enrollment in grades K-12 were 0.2, 0.5, 1.2, and 2.9 percent, respectively. For the 1-year-out prediction, this means that one would expect the projection to be within 0.2 percent of the actual value, on the average. For projections of public school enrollment in grades K-8, the MAPEs for lead times of 1, 2, 5, and 10 years were 0.3, 0.5, 1.2, and 4.3 percent, respectively, while those for projections of public school enrollment in grades 9-12 were 0.4, 0.7, 1.3, and 2.6 percent for the same lead times.

For projections of total enrollment in degree-granting institutions,
an analysis of projection errors based on the past 6 editions
of Projections of Education Statistics indicates that the
MAPEs for lead times of 1, 2, and 5 years were 1.0, 0,9, and 2.2
percent, respectively. For the 1-year-out prediction, this means
that one would expect the projection to be within 1.0 percent
of the actual value, on the average. For more information on mean
absolute percentage errors, see table
A2.

Tables A1.11 and A1.12
give the rates used to calculate projections of enrollments and
basic assumptions underlying enrollment projections.

Private School Enrollment

This edition is the first report that contains projected trends in elementary and secondary enrollment by grade level in private schools produced using the grade progression rate method.

Private school enrollment data from the National Center for Education Statistics' Private School Universe Survey for 1989-90, 1991-92, 1993-94, 1995-96, 1997-98, and 1999-2000 were used to develop these projections. In addition, population estimates for 1989 to 1999 and population projections for 2000 to 2011 from the U.S. Department of Commerce, Bureau of the Census were used to develop the projections.

The grade progression rate method was used to project private elementary and secondary school enrollment. The grade progression rate method starts with 6-year-olds entering first grade and then follows their progress through private elementary and secondary schools. The method requires calculating the ratio of the number of children in one year who "survive" the year and enroll in the next grade the following year.

Projections of enrollment in private elementary and secondary schools were developed using primarily the grade progression rate method. Kindergarten and first grade enrollments are based on projected enrollment rates of 5- and 6-year-olds. These projected enrollment rates are applied to population projections of 5- and 6-year-olds developed by the Bureau of the Census.

Enrollments in grades 2 through 12 are based on projected grade progression rates. These projected rates are then applied to the current enrollment by grade to yield grade-by-grade projections for future years. Enrollment rates of 5- and 6-year-olds and grade progression rates are projected using single exponential smoothing. Elementary ungraded and special enrollments and secondary ungraded and special enrollments are projected to remain constant at their 1999 levels. To obtain projections of total enrollment, projections of enrollments for the individual grades (kindergarten through 12) and ungraded and special classes were summed.

The grade progression rate method assumes that past trends in factors affecting private school enrollments will continue over the projection period. This assumption implies that all factors influencing enrollments will display future patterns consistent with past patterns. This method implicitly includes the net effect of such factors as migration, dropouts, deaths, nonpromotion, and transfers to and from public schools.

Mean absolute percentage errors (MAPEs) of the projection accuracy of private
school enrollment were not developed because these projections
were prepared for the first time using a new data source and methodology.
As additional data becomes available MAPEs can then be calculated.

State-Level

This edition contains projected trends in elementary and secondary enrollment by grade level in public schools from 2000 to the year 2011. This is the seventh report on state-level projections for public school elementary and secondary education statistics.

Public school enrollment data from the National Center for Education Statistics' Common Core of Data survey for 1970 to 1999 were used to develop these projections. This survey does not collect data on enrollment for private schools. In addition, population estimates for 1970 to 1999 and population projections for 2000 to 2011 from the U.S. Department of Commerce, Bureau of the Census were used to develop the projections.

Table A1.11 describes the
number of years, projection methods, and smoothing constants used
to project enrollments in public schools. Also included in table
A1.11 is the procedure for choosing the different smoothing
constants for the time series models.

Projections of enrollment in public elementary and secondary schools by state were developed using primarily the grade progression rate method. Kindergarten and first grade enrollments are based on projected enrollment rates of 5- and 6-year-olds. These projected enrollment rates are applied to population projections of 5- and 6-year-olds developed by the Bureau of the Census.

Enrollments in grades 2 through 12 are based on projected grade progression rates in each state. These projected rates are then applied to the current enrollment by grade to yield grade-by-grade projections for future years. Enrollment rates of 5- and 6-year-olds and grade progression rates are projected using single exponential smoothing. Elementary ungraded and special enrollments and secondary ungraded and special enrollments are projected to remain constant at their 1998 levels. To obtain projections of total enrollment, projections of enrollments for the individual grades (kindergarten through 12) and ungraded and special classes were summed.

The grade progression rate method assumes that past trends in factors affecting
public school enrollments will continue over the projection period.
This assumption implies that all factors influencing enrollments
will display future patterns consistent with past patterns. Therefore,
this method has limitations when applied to states with unusual
changes in migration rates. This method implicitly includes the
net effect of such factors as migration, dropouts, deaths, nonpromotion,
and transfers to and from private schools.

The sum of the projections of state enrollments was adjusted to
equal the national projections of public school K-12, K-8, and
9-12 enrollments shown in table 1.
For details on the methods used to develop the national projections
for this statistic, see the section on national enrollment projections
in this appendix.